Unusual Formation of Point Defect Complexes in the Ultra-wide Band Gap Semiconductor beta-Ga2O3

Abstract

Understanding the unique properties of ultra-wide band gap semiconductors requires detailed information about the exact nature of point defects and their role in determining the properties. Here, we report the first direct microscopic observation of an unusual formation of point defect complexes within the atomic scale structure of beta-Ga2O3 using high resolution scanning transmission electron microscopy (STEM). Each complex involves one cation interstitial atom paired with two cation vacancies. These divacancy - interstitial complexes correlate directly with structures obtained by density functional theory, which predicts them to be compensating acceptors in beta-Ga2O3. This prediction is confirmed by a comparison between STEM data and deep level optical spectroscopy results, which reveals that these complexes correspond to a deep trap within the band gap, and that the development of the complexes is facilitated by Sn doping through the increase in vacancy concentration. These findings provide new insight on this emerging material's unique response to the incorporation of impurities that can critically influence their properties.

References in corpus (2)

• Donors and Deep Acceptors in $\beta$-Ga2O3
• Computational identification of Ga-vacancy related electron paramagnetic resonance centers in $\beta$-Ga${}_2$O${}_3$

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• Measurements and Numerical Calculations of Thermal Conductivity to Evaluate the Quality of β-Gallium Oxide Thin Films Grown on Sapphire and Silicon Carbide by Molecular Beam Epitaxy
• Quantitative Modeling of Point Defects in $\beta$-Ga2O3 Combining Hybrid Functional Energetics with Semiconductor and Processes Thermodynamics
• Ultrafast Dynamics of Gallium Vacancy Charge States in $\beta$-Ga${}_2$O${}_3$
• Identifying Split Vacancy Defects with Machine-Learned Foundation Models and Electrostatics
• Spontaneous Donor Defects and Voltage-Assisted Hole Doping in Beta-Gallium Oxides under Multiple Epitaxy Conditions
• Origin of donor compensation in monoclinic (Al${}_x$Ga${}_{1-x}{)}_2$O${}_3$ alloys